The invention relates to a power converter module with a cooled busbar arrangement.
Power converter modules of the generic type, in particular for relatively high powers, are commercially available. In the case of such power converter modules, their power semiconductor modules, in particular turn-off power semiconductor modules, are connected to connections of the power converter module by a low-inductance busbar arrangement. This is achieved by virtue of the fact that the busbars used are embodied in planar fashion and stacked one above another to form a busbar stack. An insulating layer embodied in planar fashion is arranged in each case between two planar busbars. These insulating layers project beyond the planar busbars in order that limit values for air clearances and creepage paths can be complied with. Consequently, such a low-inductance busbar arrangement has at least two busbars and at least one insulating layer. In order that the busbar arrangement of the employed power semiconductor modules of the power converter module is configured as compactly as possible, this busbar assembly is laminated. By virtue of the materials used, in particular the lamination material, and the plastic used, this busbar arrangement has a temperature limit of 105° C., for example.
Since, in the commercially available power semiconductor modules, in particular turn-off power semiconductor modules, for example Insulated Gate Bipolar Transistor (IGBT), the current-carrying capacity continuously increases, the current density correspondingly increases in the busbars of a busbar arrangement, in particular of a laminated busbar arrangement, of a power converter module. This results in a quadratic increase in the losses in the busbar arrangement, such that the temperature of this busbar arrangement likewise increases and cannot be lowered by means of the baseplate of a semiconductor module or the cooling body thereof. The limit temperature of a busbar arrangement is determined by the employed materials of the insulating layers, of the lamination material and of the adhesive. Preferably, at the present time, use is made of busbar arrangements that are laminated in power converter modules with an insulating film. In this case, the lamination material of the laminated busbar arrangement sets a temperature limit. For power converter applications, this means a power limitation which is no longer governed by the power semiconductor modules used, but rather by the maximum limit temperature of the corresponding lamination material of the busbar arrangement.
Obvious solutions to this problem include, firstly, increasing the cross section of each busbar of the busbar arrangement, and, secondly, cooling this busbar arrangement, for example by inherent convection. By increasing the cross sections of the busbars of the busbar arrangement, such a busbar arrangement not only is more costly, but also has a higher weight. In order to cool the busbar arrangement by inherent convection, it has to be arranged in a power converter apparatus in such a way that a cooling air stream can flow over this busbar arrangement.
WO 2005/109505 A1 discloses a power semiconductor circuit whose busbar arrangement is cooled. In the case of this power semiconductor circuit, at least one module is soldered on the outer side on a plate-type busbar serving as positive or negative plate. The positive and negative busbars are usually arranged as topmost and bottommost plates, respectively, on a plate busbar assembly. This top busbar, on which the module is applied, is cooled directly by a cooling device, wherein this cooling device is embodied as air or liquid cooling. This cooling device is arranged in a sandwich-like manner between the top busbar and, with the interposition of an insulation, a further plate-type busbar lying in a parallel plane. Furthermore, a busbar on the underside is provided with the interposition of a further insulating layer. These busbars form together with the cooling device a very compact arrangement. The elements of this busbar assembly are connected to one another by lamination. Since this power semiconductor circuit is an inverter, two intermediate circuit capacitors are arranged below this busbar assembly, these capacitors being connected to the upper and lower busbars, respectively, by means of screw connections.
DE 10 2007 003 875 A1 discloses a power converter module comprising at least two power semiconductor modules which are mechanically connected to a cooling body in a thermally conductive manner and are electrically interconnected by means of a laminated busbar arrangement. At least one busbar of this laminated busbar arrangement is thermally linked to the cooling body by means of at least one electrically insulating and thermally conductive supporting element. By means of these supporting elements, at least one busbar of the laminated busbar arrangement is thermally linked to the cooling body. The magnitude of the heat to be dissipated determines the number of thermally conductive supporting elements. By means of these supporting elements, the laminated busbar arrangement is likewise supported in the edge regions. The quantity of heat to be dissipated from the laminated busbar arrangement is restricted by means of these thermally conductive supporting elements.
The invention is based on the object, then, of specifying a power converter module, from the busbar arrangement of which heat can be dissipated using simple means, wherein this power converter module does not have to be rerouted or redesigned.